Building with clay could change sustainable construction

Imagine standing in front of a multi-million pound building in the center of the French city of Lyon. With its rammed earth walls, it exudes warmth and history. Two hundred miles away, a small house in the Beaucastel winery in Provence has a similar structure and aesthetic.

The soil for both buildings was excavated earth that was considered waste, left over from the construction site or dug up from the surrounding area. It was destined for the landfill.

Once mixed with water and compacted, it creates a material strong enough to build walls. But watch out for fakes. It should not be confused with cement-stabilized rammed earth, which requires large amounts of cement due to the necessary wall thicknesses.

Cement production alone contributes to 3% of global greenhouse gas emissions. Now the construction sector must move to a more sustainable model by maximizing the use of highest value materials and eliminating waste.

Building with rammed earth could be scalable. However, despite their recyclability, energy efficiency, low-carbon nature and centuries-long history of successful applications, earthen buildings are still underrepresented in the green building movement and enjoy little respect among architects, developers and local authorities.

Most studies on earthen construction address technical challenges such as wall strength, water damage, and energy efficiency. But my research shows that the future of Earth as a building material faces challenges that go beyond purely technical issues. Why hasn't this ancient, ecological approach become a cornerstone of modern green architecture?

Some people still view soil as “poor man’s stuff,” coupled with poor engineering properties such as weaker or less resilient walls.

According to a study, mud architecture is seen as either a relic of the past or exclusive to luxury environmentalists. These sociocultural perceptions create a stigma that limits acceptance in modern building practices.

It is time to break down these outdated ideas and recognize earth as a valuable and sustainable building material. Once Earth is redefined as an opportunity, it can become the cornerstone of future sustainable cities, provided it is not stabilized by harmful components such as cement.

The soil used for construction is not the fertile topsoil for agriculture, but the subsoil that is excavated during foundation work or infrastructure work. It does not contribute to desertification or affect soil health.

Restore trust in earthen materials

The way we approach construction also needs to change. Clay materials do not behave like concrete. There are questions about their resilience to extreme weather conditions. However, if properly planned and implemented, earthen buildings can last for decades or even centuries.

Soil materials vary enormously (it is soil, after all), so some may be more susceptible to water damage than others. This makes standardization difficult. But if designed appropriately, clay buildings can achieve extraordinary longevity.

Earthmoving is a labor-intensive process without the possibility of large-scale automation and therefore often involves higher initial manufacturing costs. Because there is no well-established supply chain for clay materials, builders must source and test materials on a project-by-project basis, which increases costs.

With no taxes on carbon-intensive raw materials and high taxes on labor in Europe, earthen construction is often viewed as economically unattractive for developers. Governments can unlock the potential of earthen architecture by offering financial incentives or subsidies that make certification and insurance easier and less expensive. Accessible certifications and specific regulations for the use of clay as a building material are in high demand from practitioners.

The expansion of sustainable and recyclable earthen construction depends on disrupting the traditional supply chains of the design and construction industries. This begins with involving masons and craftsmen in design decisions to ensure plans are adapted to the earth's materials.

Building with earth is more than possible. It is practical, sustainable and necessary for a greener future. But to transform the sustainability of the construction sector, we need to break through walls.

This article is republished from The Conversation under a Creative Commons license. Read the original article.